A combination of the fact that we didn't announce that one far enough out for most people to plan with their organizations and still get decent travel/lodging rates by the time they do all their internal paperwork, plus the fact that holidays are already pretty hectic.

Three weeks away means we're already down to the wire if it takes you two weeks to finalize, and we'd like to have a confirmed list more than a week out.

People who wear the admin & dev hat are busy planning and testing so they can get in maintenance windows for major system upgrades during that time (don't forget to include ZCS). Our apologizes those who are dev-only and had availability; Feb will be just as nice of a trip if you were looking to escape the cold - along with learning of course.